Write ADR for Container Networking/CNI

[jschoone]

As a KaaS operator, I want to understand exactly what standards my CNI must fulfill by reading the relevant ADR.

Definition of Ready:

• User Story is small enough to be finished within one sprint
• User Story is clear and understood by the whole team
• Acceptance criteria are defined
• Acceptance criteria are clear and understood by the whole team

Definition of Done:

• All acceptance criteria are met
• Changes have been reviewed
• CI tests have run successfully
• Documentation has been updated
• Release Notes have been updated

[jschoone]

As discussed in Container Meeting

[guettli]

First version of PR was created yesterday: #322

[NotTheEvilOne]

So far the following features are required / expected at the date of writing:

• Basic CNI plugin capabilities [1]
• Host based firewall (see also Network Policy)
• Gateway API [2] features HTTPRoute and TLSRoute [3]
• Network Policy [4] [5]

The relevant document may be extended after team review.

[1] https://kubernetes.io/docs/concepts/extend-kubernetes/compute-storage-net/network-plugins/
[2] https://gateway-api.sigs.k8s.io/
[3] SovereignCloudStack/k8s-cluster-api-provider#710
[4] #769
[5] https://kubernetes.io/docs/concepts/services-networking/network-policies/#behavior-of-to-and-from-selectors

[mbuechse]

Is this a duplicate of #769? It sure seems so to me.